In general, a silver halide photographic material has heretofore comprised a light absorbing compound in a silver halide emulsion layer or other hydrophilic colloidal layers to absorb light of a specific wavelength for the purpose of adjusting sensitivity, color temperature of light and sensitivity balance in a multilayer color light-sensitive material, improving safety to safelight or inhibiting halation.
For example, in a silver halide photographic material comprising, on a support, hydrophilic colloidal layers such as a light-sensitive silver halide emulsion layer, it is necessary to control the spectral composition of light incident upon the silver halide emulsion layer to improve the photographic sensitivity during imagewise exposure to record images on the silver halide emulsion layer. In this case, the approach normally employed comprises incorporating a dye which absorbs light of a wavelength undesired by the light-sensitive silver halide emulsion layer in a hydrophilic colloidal layer present farther from the support than the light-sensitive silver halide emulsion layer so that it serves as a filter layer which transmitts only light of the desired wavelength.
An antihalation layer is provided between the light-sensitive emulsion layer and the support or between the back side of the support and the antihalation layer to absorb harmful light reflected by the interface between the emulsion layer and the support or by the back side of the support for the purpose of improving sharpness of images.
Further, for the purpose of improving sharpness of images, the silver halide emulsion layer may comprise a dye capable of absorbing light of a wavelength range to which silver halide is sensitive to inhibit irradiation.
In particular, a silver halide photographic material for use in the photomechanical process, more particularly daylight light-sensitive material, may comprise a dye which absorbs ultraviolet light or visible light in a light-sensitive layer or a layer provided between the light source and the light-sensitive layer to improve its safety to safelight.
Moreover, X-ray sensitive materials may comprise a colored layer for improving sharpness as a crossover cut filter for eliminating crossover light.
These layers which are to be colored are often made of a hydrophilic colloid. Therefore, in order to be colored, these layers normally comprise a dye incorporated therein. Such a dye is required to satisfy the following conditions:
(1) The dye should exhibit a proper spectral absorption depending on the purpose of use;
(2) The dye should be photochemically inert. In other words, the dye should have no chemically adverse effects on the properties of the silver halide photographic emulsion layer, e.g., sensitivity drop, fading of latent images and photographic fog;
(3) The dye should be decolored but dissolved away upon photographic processing so that harmful colors are not left on the photographic light-sensitive material after processing; and
(4) The dye should exhibit an excellent age stability and should not deteriotate in the coating solution or silver halide photographic material.
In order to find dyes which meet these requirements, many efforts have been made. Examples of dyes thus proposed include pyrazolone oxonol dyes as described in British Patent 506,385, barbituric oxonol dyes as described in U.S. Pat. No. 3,247,127, azo dyes as described in U.S. Pat. No. 2,390,707, styryl dyes as described in U.S. Pat. No. 2,255,077, hemioxonol dyes as described in British Patent 584,609, melocyanine dyes as described in U.S. Pat. No. 2,493,747, cyanine dyes as described in U.S. Pat. No. 2,843,486, and methylenic benzylidene dyes as described in U.S. Pat. No. 4,420,555.
If the layer containing these dyes serves as a filter layer or an antihalation layer, it is necessary that the layer be selectively colored without substantially coloring the other layers. This is because that if the other layers are also substantially colored, it not only causes a harmful spectral effect on the other layers but also eliminates the effects provided by the filter layer or antihalation layer. Further, when a dye which has been incorporated in a specific layer for the purpose of inhibiting irradiation diffuses into and colors other layers, problems similar to those described above occur.
As an approach for solving these problems, an approach is known which comprises localizing an acidic dye containing a sulfo group or a carboxyl group in a specific layer with a mordant.
Examples of such a known mordant include ethylenically unsaturated compound polymers as described in British Patent 685,475, reaction products of polyvinyl alkyl ketone and amino guanidine as described in British Patent 850,281, and vinyl pyridine polymers and vinyl pyridinium cation polymers as described in U.S. Pat. Nos. 2,548,564, 2,484,430, 3,148,061, and 3,756,814. In order to effectively mordant the above mentioned acidic dye, a cationic mordant containing secondary and tertiary amino groups, nitrogen-containing heterocyclic groups and quaternary cation groups in a polymer is used.
However, the mordanting process is disadvantageous in that when the layer in which a dye is incorporated comes into contact with other hydrophilic colloidal layers in a wet state, the dye often partially diffuses into the other hydrophilic layers. Of course, the dye diffusion depends on the chemical structure of the mordant. The dye diffusion also depends on the chemical structure of the dye used.
If a high molecular weight mordant is used, remaining color remaining can easily occur on the light-sensitive material after photographic processing, particularly shortened photographic processing. This occurs because the mordant exhibits a very weak bond strength but does have some bond strength, with the dye in an alkaline solution, such as the developer; therefore, the dye or reversible decolored products partially remain in the layer containing the mordant.
However, these cationic mordants may undergo static interaction with gelatin which is often used as a hydrophilic colloid and a surface active agent containing an alcoholate group, a carboxylate group, a sulfonate group or a sulfate group which is normally used as coating aid to prevent deterioration of coating properties.
These cationic mordants may also cause deterioration of desilvering properties and a sensitivity drop in the layers adjacent to the mordant-containing layer in a color light-sensitive material.
With such a mordant, very often the above mentioned dye diffuses into other layers. Therefore, it has been proposed to use such a mordant in a larger amount to inhibit diffusion. However, even with this approach, diffusion cannot be completely eliminated. Further, with this approach, the layer in which the mordant is incorporated needs to be thicker, causing deterioration of sharpness.
In the processing of light-sensitive material for printing process, reduction with a reducer is normally effected to adjust density and gradation. However, since the reducer contains a water-soluble iron complex as a reducing agent, the above mentioned cationic mordant undergoes static bonding with the iron complex to cause yellow stain with the iron complex.
These disadvantages can be eliminated by the use of a dye as described in JP-A-63-280246 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"). However, this approach is disadvantageous in that decolorability leaves much to be desired in low pH rapid processing.
Further, in a color light-sensitive material, colloidal silver has previously been used for the purpose of inhibiting absorption of yellow light and halation. However, the use of colloidal silver is disadvantageous in that fog in the light-sensitive silver halide emulsion layer adjacent to the colloidal silver layer becomes more remarkable. Elimination of these difficulties has been sought.
Other approaches for retaining a dye in a specific layer in the photographic light-sensitive material include known approaches which comprise allowing a dye to be present in the form of disperse solid as disclosed in JP-A-56-12639, 55-155350, 55-155351, 52-92716, 63-197943, 63-27838, and 64-40827, European Patents 0015601B1 and 0276566A1, and International Patent Application Disclosure 88/04794.
However, these approaches are obviously characterized absorption spectrum of disperse solid-coated material such that the absorption peak is shifted as compared to that of the same dye in the form of solution or in a form dissociated at pH 10, widening the half band width (HBW).
The widening of the half band width may be suitable for a filter for use where exposure is required in a wide wavelength range but is generally disadvantageous since it reduces the value of absorbance. Further, an excessively wide half band width is rather disadvantageous in a multilayer silver halide photographic material when a filter for shutting off light of undesired wavelength in the spectral sensitivity range of a lower layer such as yellow filter and magenta filter is used or when a disperse solid dye is used as safelight filter layer as described in JP-A-2-110453. Moreover, if the dye is incorporated in an antihalation layer in a light-sensitive layer having a very narrow spectral sensitivity range or if the dye is incorporated in an antihalation layer for exposure to light of a very narrow wavelength range, the low absorbance leads to the requirement of a large coated amount of dye, causing many disadvantages such as deterioration of decolorability, increase in thickness and cost rise.